1. Field of the Invention
The invention relates to a device for transmitting optical signals between units that are rotatable relative to each other, which device is also known as a rotary coupling or a rotary joint. With this, preferably a plurality of optical signals can be transmitted simultaneously in a plurality of channels.
2. Description of the Related Art
Various transmission systems are known for transmitting optical signals between units that are rotatable relative to each other.
U.S. Pat. No. 5,568,578 discloses an optical rotating data transmission device for a plurality of channels, with a Dove prism. For coupling light into or out of glass fibers, an arrangement with a plurality of GRIN lenses is provided. The GRIN lenses and glass fibers connected thereto extend along a longitudinal direction of the arrangement. Therefore a rotating optical data transmission device of this kind will have a relatively long overall length.
Another kind of an optical rotating data transmission device is disclosed in WO 01/98801. This sets out a micro-optical system having optical and mechanical parts as a one-piece component. The arrangement allows an achievement of a substantially higher packing density of individual glass fibers. The disadvantage of this system is also the long overall length.